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Primary production in terrestrial ecosystems is sustained by plants, microbiota, and fungi, which are the major organic matter providers in the root zone, setting in motion the soil food webs. Predators like soil amoebae voraciously feed on bacteria, fungi, and microbial eukaryotes releasing the nutrients sequestered in their biomass. Early food web setting up is crucial for seedling nutrition and its further development after establishment. Mycorrhizal fungi are more than phosphorus providers, and we wonder what their role is in structuring the predators' trophic groups in the root zone. We evaluated the effect of Rhizophagus intraradices inoculated in Zea mays (mycorrhizosphere), on the structuration of amoebae trophic groups along vertical and horizontal (3, 6, and 9 cm) soil distribution when compared to un-inoculated plants, after 20 days in microcosms. Amoebae species richness was highest in non-mycorrhizal seedlings in the root zone at 6- to 9-cm depth, and 3 cm away from plants. More bacterial species are needed when plants are devoid of mycorrhiza, and their influence is constrained 3 cm away from roots. Higher diversity of trophic groups was recorded at mycorrhizal seedlings and at the compartment influenced by the mycelium at 6- to 9-cm depth. The highest bacterivorous diversity, higher number of rare species and protozoa-eating amoebae, and the absence of fungivorous group recorded at the mycorrhizosphere of Z. mays, indicate that the community was very different from the non-mycorrhizal plants. We conclude that the arbuscular mycorrhizal fungus exerts significant changes on the community of trophic groups of amoebae. [ABSTRACT FROM AUTHOR]

Evolution experiments with free-living microbes have radically improved our understanding of genome evolution and how microorganisms adapt. Yet there is a paucity of such research focusing on strictly host-associated bacteria, even though they are widespread in nature. Here, we used the Acanthamoeba symbiont Protochlamydia amoebophila , a distant relative of the human pathogen Chlamydia trachomatis and representative of a large group of protist-associated environmental chlamydiae, as a model to study how obligate intracellular symbionts evolve and adapt to elevated temperature, a prerequisite for the pivotal evolutionary leap from protist to endothermic animal hosts. We established 12 replicate populations under two temperatures (20 °C, 30 °C) for 510 bacterial generations (38 months). We then used infectivity assays and pooled whole-genome resequencing to identify any evolved phenotypes and the molecular basis of adaptation in these bacteria. We observed an overall reduction in infectivity of the symbionts evolved at 30 °C, and we identified numerous nonsynonymous mutations and small indels in these symbiont populations, with several variants persisting throughout multiple time points and reaching high frequencies. This suggests that many mutations may have been beneficial and played an adaptive role. Mutated genes within the same temperature regime were more similar than those between temperature regimes. Our results provide insights into the molecular evolution of intracellular bacteria under the constraints of strict host dependance and highly structured populations and suggest that for chlamydial symbionts of protists, temperature adaptation was facilitated through attenuation of symbiont infectivity as a tradeoff to reduce host cell burden. [ABSTRACT FROM AUTHOR]

Lipid droplets (LDs) are dynamic and versatile organelles present in most eukaryotic cells. LDs consist of a hydrophobic core of neutral lipids, a phospholipid monolayer coat, and a variety of associated proteins. LDs are formed at the endoplasmic reticulum and have diverse roles in lipid storage, energy metabolism, membrane trafficking, and cellular signaling. In addition to their physiological cellular functions, LDs have been implicated in the pathogenesis of several diseases, including metabolic disorders, cancer, and infections. A number of intracellular bacterial pathogens modulate and/or interact with LDs during host cell infection. Members of the genera Mycobacterium, Legionella, Coxiella, Chlamydia, and Salmonella exploit LDs as a source of intracellular nutrients and membrane components to establish their distinct intracellular replicative niches. In this review, we focus on the biogenesis, interactions, and functions of LDs, as well as on their role in lipid metabolism of intracellular bacterial pathogens. [ABSTRACT FROM AUTHOR]

The presence of global spatial autocorrelation usually leads to the spurious identification of spatial hotspots and hinders the identification of local hotspots. Despite the use of statistical methods to address global spatial autocorrelation in spatial hotspot detection, accurately modeling global spatial autocorrelation structure without the stationarity assumption of spatial processes is difficult. To overcome this challenge, we fitted the global spatial autocorrelation structure from a geometric perspective and identified the optimal global spatial autocorrelation structure by analyzing the variances in spatial data. Hotspots were detected from the residuals obtained by removing the global spatial autocorrelation structure from the original dataset. We upgraded a weighted moving average method based on binomial coefficients (Yang Chizhong filtering) to fit the global spatial autocorrelation structure for field-like geographic phenomena. A variance decay indicator, based on the variance in the original and filtered data, was used to identify the optimal global spatial autocorrelation structure. Yang Chizhong filtering does not require a spatial stationarity assumption and can preserve local autocorrelation structures in the residuals as much as possible. Experimental results showed that hotspot detection methods combined with Yang Chizhong filtering can effectively reduce type-I and -II errors in the results and discover implicit and valuable urban hotspots. [ABSTRACT FROM AUTHOR]

Consisting of diverse groups of organisms, parasites are among the least studied pathogens despite their enormous impacts on humans, livestock, and wildlife. In particular, little is known about their host specificity and diversity in wildlife. Here, using multiple primer pairs and sequencing 18S rRNA genes of diverse groups of parasites, we aimed to investigate fecal parasitomes of carnivorous wildlife in Korea, namely, the raccoon dog (Nyctereutes procyonoides), the leopard cat (Prionailurus bengalensis), and the Eurasian otter (Lutra lutra). A total of 5 host-specific parasite species were identified, including 2 from raccoon dogs, 2 from leopard cats, and 1 from Eurasian otters. In addition, numerous parasite species of their prey animals were detected in their feces. It was found that the parasitome composition varied between host animals, and it was thought that the difference was attributed to the difference in prey animals, as numerous small mammal parasites were detected from feces of leopard cats inhabiting inland areas and fish parasites from feces of Eurasian otters and raccoon dogs inhabiting waterside areas. Furthermore, 5 zoonotic parasites known to infect humans were identified at the species level. Wildlife-associated zoonoses are expected to increase as the proximity between humans and wildlife increases due to urbanization. Vigilance may be necessary, such as by monitoring parasites in wildlife feces, as was done in this study. [Display omitted] • Fecal parasitomes of raccoon dogs, leopard cats, and Eurasian otters investigated. • The parasitomes varied between host animals, likely due to difference in prey. • Zoonotic parasites including nematodes and flatworms identified. • Vigilance and continuous monitoring for parasites in wildlife may be necessary. [ABSTRACT FROM AUTHOR]

Free-living amoebae (FLA) are protozoa dispersed in different environments and are responsible for different infections caused to humans and other animals. Microorganisms such as Acanthamoeba spp., Vermamoeba sp., and Naegleria sp. are associated with diseases that affect the central nervous system, in addition to skin infections and keratitis, as occurs in the genus Acanthamoeba and with Vermamoeba vermiformis. Due to the concerns of these FLA in anthropogenic aquatic environments, this work aimed to identify these microorganisms present in waters of Porto Alegre, Brazil. One litre sample was collected in two watercourses during the summer of 2022 and inoculated onto non-nutrient agar plates containing heat-inactivated Escherichia coli. Polymerase chain reaction results indicated the presence of FLA of the genera Acanthamoeba, Vermamoeba, and Naegleria in the study areas. Genetic sequencing indicated the presence of V. vermiformis and Naegleria gruberi. These aquatic and anthropogenic environments can serve as a means of spread and contamination by FLA, which gives valuable information on public health in the city. [ABSTRACT FROM AUTHOR]

Entamoeba histolytica (E. histolytica) is a parasite in humans that provokes amoebiasis. The most employed drug is metronidazole (MTZ); however, some studies have reported that this drug induces genotoxic effects. Therefore, it is necessary to explore new compounds without toxicity that can eliminate E. histolytica. Flavonoids are polyphenolic compounds that have demonstrated inhibition of growth and dysregulation of amoebic proteins. Despite the knowledge acquired to date, action mechanisms are not completely understood. The present work evaluates the effect of kaempferol against E. histolytica trophozoites and in the interactions with neutrophils from hamster, which is a susceptibility model. Our study demonstrated a significant reduction in the amoebic viability of trophozoites incubated with kaempferol at 150 μM for 90 min. The gene expression analysis showed a significant downregulation of Pr (peroxiredoxin), Rr (rubrerythrin), and TrxR (thioredoxin reductase). In interactions with amoebae and neutrophils for short times, we observed a reduction in ROS (reactive oxygen species), NO (nitric oxide), and MPO (myeloperoxidase) neutrophil activities. In conclusion, we confirmed that kaempferol is an effective drug against E. histolytica through the decrease in E. histolytica antioxidant enzyme expression and a regulator of several neutrophil mechanisms, such as MPO activity and the regulation of ROS and NO. [ABSTRACT FROM AUTHOR]

Protosteloid amoebae are a paraphyletic assemblage of amoeboid protists found exclusively in the eukaryotic assemblage Amoebozoa. These amoebae can facultatively form a dispersal structure known as a fruiting body, or more specifically, a sporocarp, from a single amoeboid cell. Sporocarps consist of one to a few spores atop a noncellular stalk. Protosteloid amoebae are known in two out of three well‐established major assemblages of Amoebozoa. Amoebae with a protosteloid life cycle are known in the major Amoebozoa lineages Discosea and Evosea but not in Tubulinea. To date, only one genus, which is monotypic, lacks sequence data and, therefore, remains phylogenetically homeless. To further clarify the evolutionary milieu of sporocarpic fruiting we used single‐cell transcriptomics to obtain data from individual sporocarps of isolates of the protosteloid amoeba Microglomus paxillus. Our phylogenomic analyses using 229 protein coding markers suggest that M. paxillus is a member of the Discosea lineage of Amoebozoa most closely related to Mycamoeba gemmipara. Due to the hypervariable nature of the SSU rRNA sequence we were unable to further resolve the phylogenetic position of M. paxillus in taxon rich datasets using only this marker. Regardless, our results widen the known distribution of sporocarpy in Discosea and stimulate the debate between a single or multiple origins of sporocarpic fruiting in Amoebozoa. [ABSTRACT FROM AUTHOR]

We diagnosed a case report of amoebic meningoencephalitis by Naegleria fowleri. This case represented the first recording in Iraq where it was not recording previously. This case was diagnosed after the death of an 18-year-old girl patient who lived in a rural area of Mosul in Iraq. Genetics detection of N. fowleri showed PCR product was 183bp for 18S rRNA gene. It was registered as the first recording of Iraqi isolate N. fowleri in GenBank with accession number OP380864.1. It is necessary to examine microscopically the cerebral spinal fluid (CSF) to observe the amoeba stages and exclude the bacterial causative. Rapid diagnosis may help in the treatment of amoebic meningoencephalitis. In addition, genetic identification can diagnose amoeba. Avoiding swimming or using freshwater contributes to prevent amoebic meningoencephalitis infection. [ABSTRACT FROM AUTHOR]

Hospital water systems are a significant source of Legionella, resulting in the potentially fatal Legionnaires' disease. One of the biggest challenges for Legionella management within these systems is that under unfavorable conditions Legionella transforms itself into a viable but non culturable (VBNC) state that cannot be detected using the standard methods. This study used a novel method (flow cytometry-cell sorting and qPCR [VFC+qPCR] assay) concurrently with the standard detection methods to examine the effect of temporary water stagnation, on Legionella spp. and microbial communities present in a hospital water system. Water samples were also analyzed for amoebae using culture and Vermamoeba vermiformis and Acanthamoeba specific qPCR. The water temperature, number and duration of water flow events for the hand basins and showers sampled was measured using the Enware Smart Flow® monitoring system. qPCR analysis demonstrated that 21.8% samples were positive for Legionella spp., 21% for L. pneumophila, 40.9% for V. vermiformis and 4.2% for Acanthamoeba. All samples that were Legionella spp. positive using qPCR (22%) were also positive for VBNC Legionella spp.; however, only 2.5% of samples were positive for culturable Legionella spp. 18.1% of the samples were positive for free-living amoebae (FLA) using culture. All samples positive for Legionella spp. were also positive for FLA. Samples with a high heterotrophic plate count (HPC ≥ 5 × 10³ CFU/L) were also significantly associated with high concentrations of Legionella spp. DNA, VBNC Legionella spp./L. pneumophila (p < 0.01) and V. vermiformis (p < 0.05). Temporary water stagnation arising through intermittent usage (< 2 hours of usage per month) significantly (p < 0.01) increased the amount of Legionella spp. DNA, VBNC Legionella spp./L. pneumophila, and V. vermiformis; however, it did not significantly impact the HPC load. In contrast to stagnation, no relationship was observed between the microbes and water temperature. In conclusion, Legionella spp. (DNA and VBNC) was associated with V. vermiformis, heterotrophic bacteria, and stagnation occurring through intermittent usage. This is the first study to monitor VBNC Legionella spp. within a hospital water system. The high percentage of false negative Legionella spp. results provided by the culture method supports the use of either qPCR or VFC+qPCR to monitor Legionella spp. contamination within hospital water systems. [ABSTRACT FROM AUTHOR]

Introduction: The concept of animacy is often taken as a basic natural concept, in part I because most cases seem unambiguous. Most entities either are or are not animate. However, human animacy judgments do not reflect this binary classification. They suggest that there are borderline cases, such as virus, amoeba, fly, and imaginary beings (giant, dragon, god). Moreover, human roles (professor, mother, girlfriend) are consistently recognized as animate by far less than 100% of human judges. Method: In this paper, I use computational modeling to identify features associated with human animacy judgments, modeling human animacy and living/non-living judgments using both bottom-up predictors (the principal components from a word embedding model) and top-down predictors (cosine distances from the names of animate categories). Results: The results suggest that human animacy judgments may be relying on information obtained from imperfect estimates of category membership that are reflected in the word embedding models. Models using cosine distance from category names mirror human judgments in distinguishing strongly between humans (estimated lower animacy by the measure) and other animals (estimated higher animacy by the measure). Discussion: These results are consistent with a family resemblance approach to the apparently categorical concept of animacy. [ABSTRACT FROM AUTHOR]

Three phases of macroscopic domains have been seen for large but finite periodic dimer models; these are known as the frozen, rough and smooth phases. The transition region between the frozen and rough region has received a lot of attention for the last twenty years and recently work has been underway to understand the rough–smooth transition region in the case of the two-periodic Aztec diamond. We compute uniform asymptotics for dimer–dimer correlations of the two-periodic Aztec diamond when the dimers lie in the rough–smooth transition region. These asymptotics rely on a formula found in Chhita and Johansson (Adv Math 294:37–149, 2016) for the inverse Kasteleyn matrix, they also apply to the infinite square grid dimer model with a variable weighting which interpolates between the rough and smooth phase (Kenyon et al. Ann Math (2) 163(3):1019–1056, 2006). In particular, we find that distant dimers initially decay exponentially when the magnetic coordinates are very close to the bounded complementary component of the associated amoebae, they then transition to a power law decay once far enough apart. [ABSTRACT FROM AUTHOR]

Bacterial endosymbionts can provide benefits for their eukaryotic hosts, but it is often unclear if endosymbionts benefit from these relationships. The social amoeba Dictyostelium discoideum associates with three species of Paraburkholderia endosymbionts, including P. agricolaris and P. hayleyella. These endosymbionts can be costly to the host but are beneficial in certain contexts because they allow D. discoideum to carry prey bacteria through the dispersal stage. In experiments where no other species are present, P. hayleyella benefits from D. discoideum while P. agricolaris does not. However, the presence of other species may influence this symbiosis. We tested if P. agricolaris and P. hayleyella benefit from D. discoideum in the context of resource competition with Klebsiella pneumoniae , the typical laboratory prey of D. discoideum. Without D. discoideum, K. pneumoniae depressed the growth of both Paraburkholderia symbionts, consistent with competition. P. hayleyella was more harmed by interspecific competition than P. agricolaris. We found that P. hayleyella was rescued from competition by D. discoideum , while P. agricolaris was not. This may be because P. hayleyella is more specialized as an endosymbiont; it has a highly reduced genome compared to P. agricolaris and may have lost genes relevant for resource competition outside of its host. [ABSTRACT FROM AUTHOR]

Simple Summary: The prevalence of Johne's disease (JD) due to Mycobacterium avium ssp. paratuberculosis (Map), responsible for considerable economic losses in the dairy industry worldwide, remains very high. In addition, recent studies have shown that Map may hamper the success of bovine tuberculosis (bTB) eradication programs due to frequent co-infection of hosts. Therefore, the risk of Map contamination by environmental sources must be studied given achieving improved control of this enzooty. Our previous work showed that environmental amoebae could function as reservoirs and vectors of these pathogenic mycobacteria. This study aims to describe amoeba-mycobacteria co-occurrence by sampling the water points of cattle herds monitored for Map and Mycobacterium bovis (M. bovis) infection. Our study showed that a wide diversity of amoebae and non-tuberculous mycobacteria (NTM) species, including Map, live closely together in water troughs of herds monitored for JD or bTB. The exact association between amoebae and mycobacteria calls for further investigation. One of the obstacles to eradicating paratuberculosis or Johne's Disease (JD) seems to be the persistence of Mycobacterium avium subsp. paratuberculosis (Map) in the environment due to its ability to survive alone or vectorized. It has been shown that Map is widely distributed in soils and water. Previously, we isolated amoebae associated with Map strains in the environment of bovines from an infected herd. This work aims to verify our working hypothesis, which suggests that amoebae may play a role in the transmission of JD. In this study, we sampled water in the vicinity of herds infected with Map or Mycobacterium bovis (M. bovis) and searched for amoebae and mycobacteria. Live amoebae were recovered from all samples. Among these amoebae, four isolates associated with the presence of mycobacteria were identified and characterized. Map and other mycobacterial species were detected by qPCR and, in some cases, by culture. This study suggests that amoebae and Map may be found in the same environment and might represent a risk of exposure of animals to pathogenic mycobacteria. These data open up new perspectives on the control measures to be put in place to prevent contamination by Map. [ABSTRACT FROM AUTHOR]

Amoebozoa include lineages of diverse ecology, behavior, and morphology. They are assumed to encompass members with the largest genome sizes of all living things, yet genomic studies in the group are limited. Trichosphaerium, a polymorphic, multinucleate, marine amoeba with a complicated life cycle, has puzzled experts for over a century. In an effort to explore the genomic diversity and investigate extraordinary behavior observed among the Amoebozoa, we used integrated omics approaches to study this enigmatic marine amoeba. Omics data, including single-cell transcriptomics and cytological data, demonstrate that Trichosphaerium sp. possesses the complete meiosis toolkit genes. These genes are expressed in life stages of the amoeba including medium and large cells. The life cycle of Trichosphaerium sp. involves asexual processes via binary fission and multiple fragmentation of giant cells, as well as sexual-like processes involving genes implicated in sexual reproduction and polyploidization. These findings are in stark contrast to a life cycle previously reported for this amoeba. Despite the extreme morphological plasticity observed in Trichosphaerium, our genomic data showed that populations maintain a species-level intragenomic variation. A draft genome of Trichosphaerium indicates elevated lateral gene transfer (LGT) from bacteria and giant viruses. Gene trafficking in Trichosphaerium is the highest within Amoebozoa and among the highest in microbial eukaryotes. [ABSTRACT FROM AUTHOR]

Given a Laurent polynomial F ∈ C [ z 1 ± 1 , ... , z n ± 1 ] , its amœba A F is the image by z = (z 1 , ... , z n) ∈ (C ∗) n ⟼ (log | z 1 | , ... , log | z n |) ∈ R n of the algebraic zero set V (F) = { z ∈ (C ∗) n ; F (z) = 0 } of the complex torus T n : = (C ∗) n . We relate here the question of the BIBO stability of a multilinear discrete time invariant system with a regular transfer function G (z 1 ,... , z n) / F (z 1 , ... , z n) , where F , G ∈ C [ z 1 ,... , z n ] are coprime or more precisely structural stability, with the geometrical study of the amœba A F . A criterion for strong and weak structural stability is expressed in terms of the position of 0 = (0 , ... , 0) ∈ R n with respect to the amœba A F . Then we propose a Monte-Carlo integration based algorithm in order to test the structural stability of a given such system. The proposed algorithm is not limited by the curse of dimensionality, as opposed to the state-of-the-art methods: It can be applied to any number of variables n. Several illustrative examples are presented and discussed. [ABSTRACT FROM AUTHOR]

Recent studies have shown that Escherichia coli can survive in different environments, including soils, and they can maintain populations in sterile soil for a long period of time. This indicates that growth-supporting nutrients are available; however, when grown in non-sterile soils, populations decline, suggesting that other biological factors play a role in controlling E. coli populations in soil. Free-living protozoa can affect the bacterial population by grazing. We hypothesized that E. coli strains capable of surviving in non-sterile soil possess mechanisms to protect themselves from amoeba predation. We determined the grazing rate of E. coli pasture isolates by using Dictyostelium discoideum. Bacterial suspensions applied to lactose agar as lines were allowed to grow for 24 h, when 4 μL of D. discoideum culture was inoculated in the center of each bacterial line. Grazing distances were measured after 4 days. The genomes of five grazing-susceptible and five grazing-resistant isolates were sequenced and compared. Grazing distance varied among isolates, which indicated that some E. coli are more susceptible to grazing by protozoa than others. When presented with a choice between grazing-susceptible and grazing-resistant isolates, D. discoideum grazed only on the susceptible strain. Grazing susceptibility phenotype did not align with the phylogroup, with both B1 and E strains found in both grazing groups. They also did not align by core genome phylogeny. Whole genome comparisons revealed that the five most highly grazed strains had 389 shared genes not found in the five least grazed strains. Conversely, the five least grazed strains shared 130 unique genes. The results indicate that long-term persistence of E. coli in soil is due at least in part to resistance to grazing by soil amoeba. [ABSTRACT FROM AUTHOR]

Symbiosis with microbes is a ubiquitous phenomenon with a massive impact on all living organisms, shaping the world around us today. Theoretical and experimental studies show that vertical transmission of symbionts leads to the evolution of mutualistic traits, whereas horizontal transmission facilitates the emergence of parasitic features. However, these studies focused on phenotypic data, and we know little about underlying molecular changes at the genomic level. Here, we combined an experimental evolution approach with infection assays, genome resequencing, and global gene expression analysis to study the effect of transmission mode on an obligate intracellular bacterial symbiont. We show that a dramatic shift in the frequency of genetic variants, coupled with major changes in gene expression, allow the symbiont to alter its position in the parasitism-mutualism continuum depending on the mode of between-host transmission. We found that increased parasitism in horizontally transmitted chlamydiae residing in amoebae was a result of processes occurring at the infectious stage of the symbiont's developmental cycle. Specifically, genes involved in energy production required for extracellular survival and the type III secretion system-the symbiont's primary virulence mechanism-were significantly up-regulated. Our results identify the genomic and transcriptional dynamics sufficient to favor parasitic or mutualistic strategies.

Abstract Background The availability of new biological platform organisms to get access to innovative products and processes is fundamental for the progress in biotechnology and bioeconomy. The amoeba Dictyostelium discoideum represents a novel host system that has recently been employed for both the discovery of new natural products and as a cell factory for the production of bioactive compounds such as phytochemicals. However, an essential parameter to evaluate the potential of a new host system is the demonstration of its scalability to allow industrial applicability. Here, we aimed to develop a bioprocess for the production of olivetolic acid, the main precursor of cannabinoids synthesized by a recently engineered D. discoideum strain. Results In this study, a sophisticated approach is described to scale-up an amoeba-based polyketide production process in stirred tank bioreactors. Due to the shear sensitivity of the cell wall lacking amoebae, the maximum local energy dissipation rate (ε max ) was selected as a measure for the hydromechanical stress level among different scales. By performing 1.6-L scale batch fermentations with different stress conditions, we determined a maximum tolerable ε max of 3.9 W/kg for D. discoideum. Further, we used this parameter as scale-up criterion to develop a bioprocess for olivetolic acid production starting from a 7-L stirred tank reactor to the industrially relevant 300-L scale with a product concentration of 4.8 µg/L, a productivity of 0.04 µg/L/h and a yield of 0.56 µg/g glucose. Conclusion We developed a robust and reliable scale-up strategy for amoeba-based bioprocesses and evaluated its applicability for the production of the cannabinoid precursor olivetolic acid. By determining the maximum tolerable hydromechanical stress level for D. discoideum, we were able to scale-up the process from shake flasks to the 300-L stirred tank reactor without any yield reduction from cell shearing. Hence, we showed the scalability and biotechnological exploitation of amoeba-based processes that can provide a reasonable alternative to chemical syntheses or extractions of phytochemicals from plant biomass.

We apply methods of machine-learning, such as neural networks, manifold learning and image processing, in order to study 2-dimensional amoebae in algebraic geometry and string theory. With the help of embedding manifold projection, we recover complicated conditions obtained from so-called lopsidedness. For certain cases it could even reach ∼ 99 % accuracy, in particular for the lopsided amoeba of F 0 with positive coefficients which we place primary focus. Using weights and biases, we also find good approximations to determine the genus for an amoeba at lower computational cost. In general, the models could easily predict the genus with over 90% accuracies. With similar techniques, we also investigate the membership problem, and image processing of the amoebae directly. [ABSTRACT FROM AUTHOR]

Intestinal amoebae are usually transmitted via ingestion of amoebic cysts in fecally contaminated water or food. However, other modes of transmission include sexual contact through anal-oral sex. While the primary role of anal cytology is the detection of anal cancer and precursor lesions, organisms can also be identified. Despite this, assessment of the clinical significance of cytologic identification of amoebae is lacking in the literature. A 10-year retrospective review of the pathology archives of 2 institutions in Boston, Massachusetts was conducted. Anal Pap tests that identified amoeba were reviewed and correlated with the medical records for investigation into clinical parameters and patient management. A total of 46 cases were identified between the 2 sites. The majority of patients were male (95.7%) and endorsed having sex with men (84.8%). Only a minority endorsed recent travel (6.5%). Most of the patients were also HIV (human immunodeficiency virus)-positive (71.1%) with all of these patients being well-controlled on antiretroviral therapy. Most patients were asymptomatic (87.0%). On review of the anal Pap tests, the average organism number per case was 35.4. In the majority of cases, follow-up microbiology testing for confirmation and/or speciation was not performed (89.1%) and were not treated (93.5%). While identification of amoeba is possible on anal cytology, the clinical significance remains unclear as most patients were asymptomatic and not treated in this series. Ultimately, the clinical setting likely plays an important role in determination of management. • Anal Pap tests are integral in the surveillance for cancer in high-risk populations such as men who have sex with men (MSM). While this is the main use of anal Pap tests, various infections including intestinal amoeba can be identified. Despite this, there is a paucity of literature regarding the detection of amoeba on anal Pap tests. • In this 10-year, multi-institutional retrospective study, we describe the experience of 2 large academic medical centers with the detection of amoeba on anal Pap tests with investigation into the clinical significance of this finding. • A total of 46 cases were identified between the 2 sites. The vast majority were from MSM (94.8%) without recent history of travel. The majority of patients were asymptomatic (87.0%). • On follow-up, the majority of cases were not further characterized by microbiology studies (89.1%) and the vast majority of patients were not treated (93.5%). These findings question the clinical significance of this cytologic finding. [ABSTRACT FROM AUTHOR]

In this paper, we propose a method for computing and visualizing the amoeba of a Laurent polynomial in several complex variables, which is applicable in arbitrary dimension. The algorithms developed based on this method are implemented as a free web service (http://amoebas.ru), which enables interactive computation of amoebas for polynomials in two variables, as well as provides a set of precomputed amoebas and their cross-sections in higher dimensions. The correctness and running time of the proposed algorithms are tested against a set of optimal polynomials in two, three, and four variables, which are generated using Mathematica computer algebra system. The developed program code makes it possible, in particular, to generate optimal hypergeometric polynomials in an arbitrary number of variables supported in an arbitrary zonotope given by a set of generating vectors. [ABSTRACT FROM AUTHOR]

Aim Herein, the anti-parasitic activity of azoles (fluconazole and itraconazole) and 5-nitroimdazole (metronidazole) against the brain-eating amoebae: Naegleria fowleri and Balamuthia mandrillaris was elucidated. Methods and results Azoles and 5-nitroimidazole based nanoformulations were synthesized and characterized using a UV-visible spectrophotometer, atomic force microscopy, and fourier transform infrared spectroscopy. H1-NMR, EI-MS, and ESI-MS were performed to determine their molecular mass and elucidate their structures. Their size, zeta potential, size distribution, and polydispersity index (PDI) were assessed. Amoebicidal assays revealed that all the drugs and their nanoformulations, (except itraconazole) presented significant anti-amoebic effects against B. mandrillaris , while all the treatments indicated notable amoebicidal properties against N. fowleri. Amoebicidal effects were radically enhanced upon conjugating the drugs with nanoparticles. The IC50 values for KM-38-AgNPs-F, KM-20-AgNPs-M, and KM-IF were 65.09, 91.27, and 72.19 µg.mL-1, respectively, against B. mandrillaris. Whereas against N. fowleri , the IC50 values were: 71.85, 73.95, and 63.01 µg.mL-1, respectively. Additionally, nanoformulations significantly reduced N. fowleri -mediated host cell death, while nanoformulations along with fluconazole and metronidazole considerably reduced Balamuthia -mediated human cell damage. Finally, all the tested drugs and their nanoformulations revealed limited cytotoxic activity against human cerebral microvascular endothelial cell (HBEC-5i) cells. Conclusion These compounds should be developed into novel chemotherapeutic options for use against these distressing infections due to free-living amoebae, as currently there are no effective treatments. [ABSTRACT FROM AUTHOR]

The virome of the human oral cavity and the relationships between viruses and diseases such as periodontitis are scarcely deciphered. Redondoviruses were reported in the human oral cavity in 2019, including in periodontitis patients. Here, we aimed at detecting redondoviruses and at searching for a potential viral host in human saliva. Non-stimulated saliva was collected between December 2020 and June 2021. These samples were tested using real-time PCR regarding the presence of redondovirus and Entamoeba gingivalis DNA. Similarity searches were performed using BLAST against eukaryotic and prokaryotic sequences from GenBank. The redondovirus DNA was detected in 46% of the 28 human saliva samples. In addition, short fragments of redondovirus genomes were detected in silico within Entamoeba sequences. Finally, Entamoeba gingivalis DNA was detected in 46% of the 28 saliva samples, with a strong correlation between redondovirus DNA and E. gingivalis DNA detections, in 93% of the cases. Regarded together, these findings and previous ones strongly support the presence of redondoviruses in the human oral cavity and their association to E. gingivalis as their likely host. [ABSTRACT FROM AUTHOR]

Objectives: Endolimax is a protozoan genus belongs to Amoebida order. The member of this genus occurrence in a vast range of vertebrate and invertebrate, but the species of this genus are not well studied. This review aimed to provide an updated list and some summarized information on Endolimax species, which were identified in human and animals up to the 2023. Methods: The present study was carried out to evaluate the Endolimax species with a broad review of the literature, books and electronic databases such as ISI Web of Science, PubMed, Scopus, Science Direct and Google Scholar until 2023. The hosts, pathogenicity, synonyms and distribution of valid species were considered and recorded. Results: Totally 20 defined species of Endolimax were found. Among them, only 12 species of Endolimax have been accepted as valid species. The valid species arranged by the host, including 1 species in human, 2 species in rodents, 1 species in birds, 2 species in reptiles, 1 species in amphibian, 4 species in arthropod and 1 species in fishes. Conclusion: Intensive studies are needed in order to identification of other new and valid species in different animals and their characteristics. [ABSTRACT FROM AUTHOR]

Two conspicuous wet shifts in the peat stratigraphy of Store Mosse in southern Sweden, associated with bog‐wide changes in vegetation and degree of peat decomposition, were analysed at high resolution. The bog‐surface wetness (BSW) proxy data (organic matter bulk density, C/N ratio, plant macrofossils and testate amoebae) highlight the importance of interactions between vegetation composition, microtopography and degree of peat decomposition, and show that the bog system operated consistently during the two wet shifts (dated to c. 2700 and 1000 cal a bp) despite different internal and external conditions. A sensitive bog‐system state, associated with a degraded microtopography and well‐decomposed surface peat with low hydrological conductivity developed during sustained dry conditions, probably contributed to the large BSW amplitudes registered. Comparable bog systems are expected to operate in the same way, and regionally high sensitivity that developed in response to atmospheric circulation changes may partly explain synchronous registration of wet shifts. The wet shifts in Store Mosse were attributed to solar and volcanic forcing, respectively, and wet shifts of similar magnitude registered in other NW European bogs are likely to also have been externally forced. [ABSTRACT FROM AUTHOR]

Amoebae are one major group of protists that are widely found in natural and engineered environments. They are a significant threat to human health not only because many of them are pathogenic but also due to their unique role as an environmental shelter for pathogens. However, one unsolved issue in the amoeba–bacteria relationship is why so many bacteria live within amoeba hosts while they can also live independently in the environments. By using a facultative amoeba– Paraburkholderia bacteria system, this study shows that facultative bacteria have higher survival rates within amoebae under various environmental stressors. In addition, bacteria survive longer within the amoeba spore than in free living. This study demonstrates that environmental stress can promote the persistence of facultative bacterial symbionts in amoebae. Furthermore, environmental stress may potentially select and produce more amoeba‐resisting bacteria, which may increase the biosafety risk related to amoebae and their intracellular bacteria. [ABSTRACT FROM AUTHOR]

We present the case of a 61-year-old woman with a history of orthotopic heart transplant who was hospitalized with new-onset headache. Magnetic resonance imaging (MRI) of the brain revealed T2 hyperintense signal involving the left occipital lobe with leptomeningeal enhancement and mild vasogenic edema. Initial neurologic examination was normal; however, after 7 days she developed imbalance, visual disturbances, night sweats, bradyphrenia, alexia without agraphia, and right hemianopsia. Brain MRI showed enlargement of the left occipital mass and worsening edema. Stereotactic needle biopsy showed nondiagnostic necrosis. The patient continued to deteriorate despite dexamethasone. Cerebrospinal fluid (CSF) suggested infection, and cytomegalovirus CSF polymerase chain reaction (PCR) was positive. The patient received vancomycin, imipenem, and ganciclovir. After obtaining a positive serum beta-D-glucan (Fungitell), amphotericin was added. Despite best medical efforts, the patient died. Postmortem broad-range PCR sequencing of the brain tissue was positive for rare amoeba Balamuthia mandrillaris. [ABSTRACT FROM AUTHOR]

The genus Schizoplasmodiopsis is one of the most morphologically diverse groups among the class Variosea. Recent phylogenetic studies suggest that Schizoplasmodiopsis is polyphyletic, but there are few taxonomic studies of this genus. We established S. micropunctata strain YIP-40, observed in detail its of morphology and lifecycle, and conducted a phylogenetic analysis. The phylogenetic analysis revealed that S. micropunctata was sister to Tychosporium acutostipes. Scanning electron microscopy showed S. micropunctata had a non-deciduous hilum structure that is unique to Tychosporium. The morphology of amoebae, mitotic behavior, and prespore cells of S. micropunctata also supported the close relationship to Tychosporium. We propose to transfer S. micropunctata to Tychosporium and emend the generic concept of Tychosporium to include this species. [ABSTRACT FROM AUTHOR]

Two multinucleate amoebae species, nowadays belonging to the genus Thecochaos, were never seen alive since 1913. Stained preparations deposited with the British Museum of Natural History (London) by E. Penard remain the only material proof of the existence of these organisms. We recently found an amoeba, identified as Thecochaos fibrillosum, in the soil sample originating from Chernevaya taiga soil in South Siberia (Russia). In total, we have got 15 cells of this species; however, using this amount of cells, we performed light- and electron-microscopic study, made permanent stained preparations, obtained SSU rRNA gene sequence using single-cell DNA isolation technique, and performed NGS sequencing to obtain genomic data for multigene analysis. Its SSU gene is unusually short (1586 bp), has significant losses in many laps, and, to the moment, is the shortest one known among Amoebozoa. The SSU sequence of this species robustly groups within the family Thecamoebidae as a sister to Thecamoeba/Sappinia clade. Multigene analysis either supported this position of Thecochaos or suggested its grouping with Sappinia. This study demonstrates that modern single-cell techniques allow correct and complete study and description of rare and almost non-cultivable amoebae species. [ABSTRACT FROM AUTHOR]

Multilamellar bodies (MLBs) are membrane-bound cytoplasmic organelles of lysosomal origin. In some protozoa, they were considered as lipid storage secretory organelles and feasible participants in cell-to-cell communication. However, for Acanthamoeba castellanii, similar vesicles were indicated only as possible transmission vectors of several pathogenic bacteria without attributing them biological roles and activities. Since amoebae belonging to the genus Acanthamoeba are not only of environmental but also of clinical significance, it is of great importance to fully understand their physiology. Thus, determination of MLB lipid composition could partly address these questions. Because MLBs are secreted by amoebae as a result of bacteria digestion, the co-culture technique with the use of "edible" Klebsiella aerogenes was used for their production. Lipids obtained from The MLB fraction, previously purified from bacterial debris, were analyzed by high-performance thin-layer chromatography, gas chromatography coupled with mass spectrometry, and high-resolution mass spectrometry. Lipidomic analysis revealed that in MLBs, a very abundant lipid class was a non-phosphorous, polar glycerolipids, diacylglyceryl-O-(N,N,N)-trimethylhomoserine (DGTS). Since DGTSs are regarded as a source of nitrogen and fatty acids, MLBs can be considered as lipid storage organelles produced in stress conditions. Further, the identification of phytoceramides and possible new betaine derivatives indicates that MLBs might have a distinct bioactive potential. [ABSTRACT FROM AUTHOR]

ABSTRACT The diatom Phaeodactylum tricornutum is regarded as a prospective “cell factory” for the high-value products fucoxanthin and eicosapentaenoic acid (EPA). However, contamination with grazing protozoa is a significant barrier to its commercial cultivation. Here, we describe a new species of heterolobosean amoeba, Euplaesiobystra perlucida, which caused the loss of Phaeodactylum tricornutum in pilot-scale cultures. Morphological and molecular characteristics distinguish E. perlucida from the other species in the genus Euplaesiobystra. E. perlucida is 1.4 to 3.2 times larger than other Euplaesiobystra species in terms of average length/width and maximum length/width of the trophozoites. Unlike Euplaesiobystra salpumilio, E. perlucida has no cytostome; E. perlucida lacks a flagellate stage, whereas Euplaesiobystra hypersalinica and E. salpumilio both display a flagellate stage in their life cycle. The small-subunit rRNA gene sequence of E. perlucida shared only 88.02% homology with that of its closest relative, Euplaesiobystra dzianiensis, and had two distinctive regions. Its phylogenetic branch was clustered with one uncultured heterolobosean clone (bootstrap support/posterior probability = 100%/1.00). Results of feeding experiments demonstrated that E. perlucida could graze on various unicellular and filamentous eukaryotic microalgae (chlorophytes, chrysophytes, euglenids, and diatoms) and cyanobacteria. E. perlucida’s ingestion rate declined exponentially with increasing size of unicellular prey, and E. perlucida attained the highest growth rates on P. tricornutum. On the basis of its strong ability to graze on microalgae, capacity to form large populations in a short period of time, and capacity to form resistant resting cysts, this contaminant has the potential to cause severe problems in large-scale microalgal culture and merits further attention. IMPORTANCE Heteroloboseans have garnered considerable interest because of their extraordinary ecological, morphological, and physiological diversity. Many heteroloboseans have adapted to various extensive habitats, including halophilic, acidophilic, thermophilic, psychrophilic, and anaerobic habitats. Most heteroloboseans are bacterivores, with a few algivorous species reported. In this study, a new species of algivorous heterolobosean amoeba, Euplaesiobystra perlucida, is described as a significant grazer that causes losses in outdoor industrial Phaeodactylum cultures. This study provides phenotypic, feeding, and genetic information on a previously unknown heterolobosean, emphasizes the impact of contaminating amoebae in commercial microalgal cultures, and will contribute to the management strategies for predicting this kind of contaminant in large-scale microalgal cultivation.

Bacterial persisters are a transient subpopulation of non-growing, antibiotic-tolerant cells. There is increasing evidence that bacterial persisters play an important role in treatment failure leading to recurring infections and promoting the development of antibiotic resistance. Current research reveals that recurring legionellosis is often the result of relapse rather than reinfection and suggests that the mechanism of bacterial persistence may play a role. The development of single-cell techniques such as the Timerbac system allows us to identify potential persister cells and investigate their physiology. Here, we tested the persister forming capacity of 7 pairs of Legionella pneumophila (Lp) clinical isolates, with isolate pairs corresponding to two episodes of legionellosis in the same patient. We distinguished non-growing subpopulations from their replicating counterparts during infection in an amoeba model. Imaging flow cytometry allowed us to identify single non-growing bacteria within amoeba cells 17 h post-infection, thus corresponding to this subpopulation of potential persister cells. Interestingly the magnitude of this subpopulation varies between the 7 pairs of Lp clinical isolates. Biphasic killing kinetics using ofloxacin stress confirmed the persister development capacity of ST1 clinical isolates, highlighting enhanced persister formation during the host cell infection. Thus, persister formation appears to be strain or ST (sequence type) dependent. Genome sequence analysis was carried out between ST1 clinical isolates and ST1 Paris. No genetic microevolution (SNP) linked to possible increase of persistence capacity was revealed among all the clones tested, even in clones issued from two persistence cycle experiments, confirming the transient reversible phenotypic status of persistence. Treatment failure in legionellosis is a serious issue as infections have a 5-10% mortality rate, and investigations into persistence in a clinical context and the mechanisms involved may allow us to combat this issue.

We perform a detailed statistical analysis of diffusive trajectories of membrane-enclosed vesicles (vacuoles) in the supercrowded cytoplasm of living Acanthamoeba castellanii cells. From the vacuole traces recorded in the center-of-area frame of moving amoebae, we examine the statistics of the time-averaged mean-squared displacements of vacuoles, their generalized diffusion coefficients and anomalous scaling exponents, the ergodicity breaking parameter, the non-Gaussian features of displacement distributions of vacuoles, the displacement autocorrelation function, as well as the distributions of speeds and positions of vacuoles inside the amoeba cells. Our findings deliver novel insights into the internal dynamics of cellular structures in these infectious pathogens. [ABSTRACT FROM AUTHOR]

Background and Aim Acanthamoeba is one of free-living amoebas, which are very abundant in nature. As a free-living amoeba, this parasite has a very high lethality, especially in people with underlying diseases, so researchers are always looking for a way to combat it. Drug plants are a good way to fight Acanthamoeba species. In this study, we aimed to investigate the lethal effect of the extract of Oliveria decumbens vent and Peganum harmala alcoholic extract on Acanthamoeba. Methods & Materials In this study using the extract from an extract of Oliveria decumbens vent and Peganum harmala with concentrations of 1.25, 2.5, 5, 10, and 20 mg/ml to investigate the lethal effect of this extract. The plant was treated with Acanthamoeba amoebae after three times (24, 48, and 72) hours. Ethical Considerations This study was approved by the Ethics Committee of the Jahrom University of Medical Sciences (Code: IR.JUMS.REC.1398.029). Results The present research showed that using different concentrations at three times (24, 48, and 72) hours the effect of the extract on trophozoites and cysts of Acanthamoeba was shown. The highest lethality is related to the concentration of 20 mg/ml using a combination of both extracts at the time 72 hours and the lowest lethality is related to the concentration of 1.25 mg/ml of Oliveria decumbens vent at the time 24 hours. Conclusion Observations indicate that the alcoholic extract of Oliveria decumbens vent and Peganum harmala had a perfect effect both separately and in a combination of both extracts. These two extracts had a synergistic effect on the lethal effect of Acanthamoeba amoeba.

Allovahlkampfia spelaea (A. spelaea) is a free-living amoeba, proved to cause Acanthamoeba-like keratitis with quite difficult treatment. This study aimed to evaluate the amoebicidal effect of Allium cepa (A. cepa) on A. spelaea trophozoites and cysts both in vitro and in vivo using Chinchilla rabbits as an experimental model of this type of keratitis. Chemical constituents of the aqueous extract of A. cepa were identified using Liquid Chromatography-mass Spectrometry (LC-MS). In vitro, A. cepa showed a significant inhibitory effect on trophozoites and cysts compared to the reference drug, chlorhexidine (CHX) as well as the non-treated control (P

Abstract Within each ecosystem, organisms and populations maintain a complex set of relationships. These interactions can determine the distribution area of a species and play an essential role in its evolution. Parasites are ubiquitous components of nature and have a high influence on various aspects of the biology and ecology of organisms, affecting the populations of their hosts and, therefore, their communities and ecosystems. Free-living amoebae are unicellular organisms that can be found in water, soil or air. Some species are of great importance in human health. In Hydra, there are several reports of Hydramoeba hydroxena infections. In this work we present a double parasitosis: two concatenated infectious periods in the host polyp of Hydra vulgaris and Hydra vulgaris pedunculata for three freshwater bodies in the province of Buenos Aires, Argentina. Hydramoeba sp. and Acanthoamoeba sp. unchain a series of anatomical lesions that in all cases cause the death of the polyps due to total disintegration. This finding becomes important at a sanitary level due to the appearance of Acanthoamoeba sp. in waters associated with human recreational activities; For the Hydra genus, the importance lies at an ecological and evolutionary level, considering the possible impact on its natural populations.

Abstract Amoebae are one major group of protists that are widely found in natural and engineered environments. They are a significant threat to human health not only because many of them are pathogenic but also due to their unique role as an environmental shelter for pathogens. However, one unsolved issue in the amoeba–bacteria relationship is why so many bacteria live within amoeba hosts while they can also live independently in the environments. By using a facultative amoeba– Paraburkholderia bacteria system, this study shows that facultative bacteria have higher survival rates within amoebae under various environmental stressors. In addition, bacteria survive longer within the amoeba spore than in free living. This study demonstrates that environmental stress can promote the persistence of facultative bacterial symbionts in amoebae. Furthermore, environmental stress may potentially select and produce more amoeba‐resisting bacteria, which may increase the biosafety risk related to amoebae and their intracellular bacteria.

We investigate two variants of splitting tree forcing, their ideals and regularity properties. We prove connections with other well‐known notions, such as Lebesgue measurablility, Baire‐ and Doughnut‐property and the Marczewski field. Moreover, we prove that any absolute amoeba forcing for splitting trees necessarily adds a dominating real, providing more support to Hein's and Spinas' conjecture that add(ISP)≤b$\operatorname{add}(\mathcal {I}_\mathbb {SP}) \le \mathfrak {b}$. [ABSTRACT FROM AUTHOR]

Understanding the interactions among the functional groups of living organisms within ecosystems is a main challenge in ecology. This question is particularly important in relation to the interactions between the above- and below-ground components of terrestrial ecosystems. We investigated the effects of macro- (geographic position and mire size) and micro-environmental (pH, water table depth, water mineralization and temperature) characteristics and vegetation composition (both vascular plants and bryophytes) on the species structure of testate amoeba assemblages in eight Sphagnum-dominated mires across the Northern Caucasus Mountains (Russia). In total, 97 testate amoeba species from 34 genera were identified. A multiple factor analysis indicated the strongest relationships between the species structure of the testate amoeba assemblages and the local vegetation, especially bryophytes, whereas the interaction with the micro-environmental characteristics was the weakest. Among the micro-environmental data, the strongest effects on the species composition of all the assemblages were detected for the pH followed by the water table depth and water temperature. The variance partitioning of the species structure of the testate amoeba assemblages in response to the abiotic and biotic data indicated that most of the variance was related to the bryophyte and vascular plant assemblages, whereas the contribution of the environmental data was lower. Moreover, most of the effects were highly related to each other, so that the proportion of the jointly explained variation was high, whereas the individual effects were much lower. [ABSTRACT FROM AUTHOR]

Among the most intriguing structural features in the known virosphere are mimivirus surface fibrils, proteinaceous filaments approximately 150 nm long, covering the mimivirus capsid surface. Fibrils are important to promote particle adhesion to host cells, triggering phagocytosis and cell infection. However, although mimiviruses are one of the most abundant viral entities in a plethora of biomes worldwide, there has been no comparative analysis on fibril organization and abundance among distinct mimivirus isolates. Here, we describe the isolation and characterization of Megavirus caiporensis, a novel lineage C mimivirus with surface fibrils organized as "clumps." This intriguing feature led us to expand our analyses to other mimivirus isolates. By employing a combined approach including electron microscopy, image processing, genomic sequencing, and viral prospection, we obtained evidence of at least three main patterns of surface fibrils that can be found in mimiviruses: (i) isolates containing particles with abundant fibrils, distributed homogeneously on the capsid surface; (ii) isolates with particles almost fibrilless; and (iii) isolates with particles containing fibrils in abundance, but organized as clumps, as observed in Megavirus caiporensis. A total of 15 mimivirus isolates were analyzed by microscopy, and their DNA polymerase subunit B genes were sequenced for phylogenetic analysis. We observed a unique match between evolutionarily-related viruses and their fibril profiles. Biological assays suggested that patterns of fibrils can influence viral entry in host cells. Our data contribute to the knowledge of mimivirus fibril organization and abundance, as well as raising questions on the evolution of those intriguing structures. IMPORTANCE Mimivirus fibrils are intriguing structures that have drawn attention since their discovery. Although still under investigation, the function of fibrils may be related to host cell adhesion. In this work, we isolated and characterized a new mimivirus, called Megavirus caiporensis, and we showed that mimivirus isolates can exhibit at least three different patterns related to fibril organization and abundance. In our study, evolutionarily-related viruses presented similar fibril profiles, and such fibrils may affect how those viruses trigger phagocytosis in amoebas. These data shed light on aspects of mimivirus particle morphology, virus-host interactions, and their evolution. [ABSTRACT FROM AUTHOR]

Mycobacterium chimaera colonizes water-based heater–cooler units (HCUs), from which it can spread to patients during surgery. Vermamoeba vermiformis is a free-living waterborne amoeba, which was consistently present within HCUs. To determine whether these amoebae can be involved in the persistent presence of M. chimaera. An in-vitro disinfection model. Increased survival of M. chimaera was observed after chlorine exposure in the presence of V. vermiformis. Confocal microscopy demonstrated the intracellular presence of M. chimaera in V. vermiformis. In this way, V. vermiformis can contribute to the persistent presence of M. chimaera in HCUs. Cleaning and disinfection protocols should take this phenomenon into account. [ABSTRACT FROM AUTHOR]

Evolutionary selection pressures that resulted in microbes found within environmental reservoirs that can cause diseases in animals are unknown. One hypothesis is that predatory organisms select microbes able to counteract animal immune cells. Here, a non-pathogenic yeast, Sporobolomyces primogenomicus , was exposed to predation by Acanthamoeba castellanii. Strains emerged that were resistant to being killed by this amoeba. All these strains had altered morphology, growing as pseudohyphae. The mutation in one strain was identified: CNA1 encodes the calcineurin A subunit that is highly conserved in fungi and where it is essential for their virulence in hosts including mammals, insects, and plants. [ABSTRACT FROM AUTHOR]

The memelement emulation using Operational Transconductance Amplifiers (OTAs) has been quite popular in the last decade. Interestingly, a detailed literature survey reveals that only voltage-biased OTAs have been used so far, for their emulators, which may be due to the ease of linear memelement function realization (through just bias voltage application by employing a capacitance). But this technique has disadvantages; most commercially available OTAs are current biased, voltage biasing does not provide a better range for tunability, and current biasing is more stable and can be easily provided through current mirrors in large circuits. Therefore, the presented work proposes a Universal memelement emulator (UME) using only current-biased Active elements (which are purely off-the-shelf). The developed UME uses four single output OTAs, one CCII (Second Generation Current Conveyor) along with only three grounded passive elements. Overall, the designed circuit configuration is based on just forty CMOS transistors, which is the least as compared to other existing UMEs. And also, the exhibited operating frequency limit is found to be in the MHz range for memristor and above 100 kHz for other realized memelements. The paper also describes the application examples of proposed UME in the relaxation oscillator and in a neuromorphic circuit exhibiting the Amoeba behavior. To verify the designed circuits, the simulations have been executed in PSPICE using 0.18 µm CMOS technology. Lastly, the realization of the proposed UME has been shown via commercial ICs; LM13700 and AD844, and results are presented. [ABSTRACT FROM AUTHOR]

We hypothesize that as one of the most consequential events in evolution, primary endosymbiosis accelerates lineage divergence, a process we refer to as the endosymbiotic ratchet. Our proposal is supported by recent work on the photosynthetic amoeba, Paulinella, that underwent primary plastid endosymbiosis about 124 Mya. This amoeba model allows us to explore the early impacts of photosynthetic organelle (plastid) origin on the host lineage. The current data point to a central role for effective population size (Ne) in accelerating divergence post‐endosymbiosis due to limits to dispersal and reproductive isolation that reduce Ne, leading to local adaptation. We posit that isolated populations exploit different strategies and behaviors and assort themselves in non‐overlapping niches to minimize competition during the early, rapid evolutionary phase of organelle integration. The endosymbiotic ratchet provides a general framework for interpreting post‐endosymbiosis lineage evolution that is driven by disruptive selection and demographic and population shifts. Also see the video abstract here: https://youtu.be/gYXrFM6Zz6Q [ABSTRACT FROM AUTHOR]

Most eukaryotic microbial biodiversity is undescribed, and most species might be morphologically indistinguishable. Notable exceptions are so-called flagship species which are highly conspicuous and can therefore be used to address biogeographical questions. Here we describe Hyalosphenia papilio subsp. paynei, an arcellinid testate amoeba (Amoebozoa; Arcellinida; Hyalospheniidae) from wet hollows in two Sphagnum peatlands, one in Wales and one in Ireland. Phylogenetic analysis based on Cytochrome C oxidase subunit I (COI) sequencing places it within the lineage A of the H. papilio complex, but it differs from all 13 known H. papilio genetic lineages by its very distinctive, wider than long, morphology. The fact that such a conspicuous taxon was never reported in hundreds of studies published on Holarctic Sphagnum peatlands since Leidy's description of H. papilio in 1874 suggests that this subspecies has not dispersed and survived beyond Britain and Ireland. Furthermore its genetic similarity to H. papilio s. str. suggests that it has recently evolved. The discovery of this new taxon calls for a more detailed analysis of the morphological, ecological and molecular diversity of the H. papilio species complex. [ABSTRACT FROM AUTHOR]